The 40-year-old former Marine Corps captain, who served four tours of duty in Iraq, has been a critic of his own party, especially House Speaker Nancy Pelosi. He was part of a coalition in the House — along with Ohio Rep. Tim Ryan, who is also running for president — that argued Democrats needed a new generation of leaders. Moulton was first elected to Congress in 2014 by knocking off an incumbent Democrat in the primary, arguing a fresh change was needed.